The invention relates to a method and apparatus for incorporating reinforcement material into a substrate. Such reinforcement may be useful in plastic, polymeric and elastomeric products.
Although there has been interest in the use of short fibers for reinforcing plastic and polymeric products for many years, the potential for such reinforcement has not been fully developed due to limitations in extrusion and mixing. Under existing processing, fibers are typically introduced into the compound as an ingredient during the mixing stage. However, such mixes are limited to short length fibers, low fiber loading and low compound viscosity because of the difficulties in processing due to the increase in compound viscosity caused by fiber incorporation. In addition, during compound mixing fibers tend to fracture and aggregate within the compound, producing pockets of poorly dispersed fibers within the compound matrix.
After mixing, fibers in a compound are generally randomly oriented. Attempts at achieving directionally oriented fibers in rubber components have been met with some, but not complete success. During extrusion and calendering, fibers in a compound tend to align in the direction of flow, although the random fiber orientation introduced during the mixing stage can never be entirely eliminated, due to the viscoelastic nature of the elastomer matrix. Thus, fiber orientation during processing can not be fully controlled, even by using highly aligning flow fields. As a consequence, complete, i.e. 100% fiber orientation cannot be achieved in the lengthwise direction of extruded or calendered components.
Although some degree of lengthwise fiber orientation can be achieved via extrusion and calendering processes, and lengthwise orientation has advantages in some applications, it is hypothesized that fibers oriented perpendicular to the surface, or in the thickness direction of a rubber component, can improve the abrasion and lateral stiffness properties of a component. However, such fiber composites cannot be produced by conventional processing operations. While very difficult to manufacture, attempts at achieving a perpendicular fiber orientation have been made by two methods. The first method is highly laborious and involves cutting sections of calendered or extruded fiber-filled components, where some degree of lengthwise fiber orientation is obtained, then rotating and plying sections of the calendered sheet side by side to provide perpendicular fiber orientation. A second method involves extruding a short-fiber reinforced compound through an abrupt expansion die that causes the extrudate sheet to fold upon itself in an accordion-like manner, so that a lamellar-type structure is obtained.
In order to perform fundamental studies in the effects that fiber composites have on properties such as abrasion and lateral stiffness, it is apparent that a new technology must first be developed that can obtain controlled fiber orientation and distribution within polymeric components.
An object of the invention is to develop a novel processing technology that will achieve precision orientation of fibers in polymeric components.
It is also an object of the invention to provide fiber reinforced composites with precisely placed and angled fiber reinforcement.
Other objects of the invention will be apparent from the following description and claims.
The invention relates to an apparatus 10 for injecting material into a substrate, the apparatus comprising a central portion 26 having a hole 30 therein for directing the path of material to be injected, a hollow needle 14 connected to a first end of central portion 26 for receiving material to be injected from central portion 26 and for penetrating a substrate, a cutter 18 associated with the apparatus 10 for separating material to be injected, a top 28 having a hole 32 associated with central portion 26 distal from the needle 14 for receiving material to be injected into apparatus 10, and clamping means 20, 22 disposed between top 28 and central portion 26 for controlling the status of the material to be injected with respect to the apparatus 10.
The first clamping means 22 is associated with top 28, and second clamping means 20 is associated with central portion 26, and central portion 26 is movable relative to top 28 and first clamping means 22. In the operation of the apparatus, the second clamping means 20 is in a locked position prior to separation of central portion 26 from top 28 and penetration of needle 14 into substrate 12, and first clamping means 22 is in an unlocked position. Also, the second clamping means 20 is in an unlocked position prior to separation of central portion 26 from top 28 and penetration of needle 14 into substrate 12, and first clamping means 22 is in a locked position.
A guard 24 provides a connection between central portion 26 and needle 14, and provides an end point or stop for the penetration of needle 14 into a substrate.
Also provided is a method for injecting a material into a substrate, the method comprising the steps of (a) providing a guide means such as a hollow needle 14 for a material to be injected, (b) directing a material to be injected into the guide means, (c) clamping the material to be injected in a stationary position relative to the guide means using a first clamping means 20 in a starting position, (d) cutting the material at a desired length, (e) inserting the guide means into a substrate to a second position, (f) releasing first clamping means 20 and engaging a second clamping means 22 to clamp the material to be injected in a stationary position independent of the guide means, (g) removing the guide means from the substrate and returning the guide means to a starting position. The cutting step (d) may take place before or after the material is injected into the substrate.
The method may comprise the further steps of using a fiber as the material to be injected, and selecting the substrate to be an elastomer.